Fuel Cell System and Method for Operating the System

ABSTRACT

The present invention is a fuel cell system including a fuel cell, an injector which is provided in a hydrogen supply channel of the fuel cell and which adjusts a gas state of an upstream side of the hydrogen supply channel to supply a gas toward a downstream side, and a control device which drives and controls the injector. The control device controls an operation of the injector based on a driving state of an associated device including the fuel cell system  1.

TECHNICAL FIELD

The present invention relates to a fuel cell system in which a gassupply channel of a fuel cell is provided with an injector, and a methodfor operating the system.

BACKGROUND ART

At present, a fuel cell system including a fuel cell which receivessupply of a reactive gas (a fuel gas and an oxidizing gas) to generate apower has been suggested and put to practical use. Such a fuel cellsystem is provided with a fuel supply channel for supplying, to the fuelcell, the fuel gas supplied from a fuel supply source such as a hydrogentank.

Moreover, in general, the fuel supply channel is provided with apressure adjustment valve (a regulator) which reduces, to a constantvalue, a supply pressure of the fuel gas from the fuel supply source, ina case where the supply pressure is remarkably high (e.g., see JapanesePatent Application Laid-Open No. 2004-342386).

DISCLOSURE OF THE INVENTION

However, in a pressure adjustment valve disclosed in Patent Document 1,a supply pressure of a fuel gas is fixed owing to a structure of thevalve, so that it is difficult to quickly change the supply pressure ofthe fuel gas based on an operating situation (i.e., a response propertyis low), and such precise pressure adjustment as to change a targetpressure in multiple stages cannot be performed.

Moreover, in the fuel cell system, a noise level of the whole system isremarkably low even in the operating situation, so that when anoperation sound is generated in each operation device, the sound mightbe a harsh noise, depending on the circumstances. Therefore, there is ademand for a system in which the supply pressure of the fuel gas canappropriately be changed based on an operation state of a fuel cell andin which awareness of a noise can be suppressed.

The present invention has been developed in view of such a situation,and an object thereof is to provide a highly responsive fuel cell systemin which a supply pressure of a fuel gas can appropriately be changedbased on an operation state of a fuel cell and in which an operator doesnot easily care about an operation sound, and a method for operating thesystem.

To achieve the above object, a fuel cell system according to the presentinvention is a fuel cell system comprising: a fuel cell which receivessupply of a gas to generate a power; an injector which is provided in agas supply channel of the fuel cell and which adjusts a state of the gason an upstream side of the gas supply channel to supply the gas to adownstream side; and control means for driving and controlling theinjector, the control means being configured to control an operation ofthe injector based on a driving state of an associated device includingthe fuel cell system.

According to such a constitution, an operation state (an opening rate ofa valve body of the injector (a gas passage area), and an opening timeof the valve body of the injector (a gas injection time) or the like)can be set based on an operation state of the fuel cell (an amount of apower to be generated by the fuel cell (a power, a current and avoltage), a temperature of the fuel cell, an abnormal state of the fuelcell system, an abnormal state of a fuel cell main body or the like).Therefore, a gas state (a supply pressure) of a fuel gas canappropriately be changed based on the operation state of the fuel cell,so that a response property can be improved.

It is to be noted that the “gas state” is a state (a flow rate, apressure, a temperature, a molecular concentration or the like) of thegas, and especially includes at least one of the gas flow rate and thegas pressure.

Moreover, the control means controls the operation of the injector basedon the driving state of the associated device including the fuel cellsystem, so that the injector can be operated, for example, in a state inwhich an operation sound of the injector does not easily become harsh,and it can be prevented that the operation sound of the injector becomesharsh.

The associated device including the fuel cell system corresponds to, forexample, a surrounding electronic device including the fuel cell system.In this case, examples of the electronic device include a pump, a motorand a fan. When the fuel cell system is mounted on a mobile body, theelectronic device can be interpreted as a traction motor, an inverter, aconverter or the like.

The controlling of the operation of the injector is, for example,allowing or limiting (prohibiting) of the operation of the injector,changing of a drive cycle of the injector or the like. For example, anoise frequency due to pulsation of the associated device (e.g., thepump) is matched with a drive frequency of the injector, the injector isoperated at a peak of a radiant sound from the associated device, or theoperation of the injector is limited (prohibited) in a case where theradiant sound from the associated device has a predetermined value orless.

In the fuel cell system, the control means may control the operation ofthe injector based on the radiant sound generated in accordance with thedriving of the associated device.

When such a constitution is employed, for example, the operation soundof the injector is superimposed on the radiant sound from the associateddevice, whereby the operation sound of the injector can be hidden orobscured by the radiant sound from the associated device, and it can beprevented that the operation sound of the injector becomes harsh.

As the associated device, for example, a pump which supplies a fluid tothe fuel cell can be applied. As the pump, an air compressor which feedsan oxidizing gas under pressure to the fuel cell is applicable.

Moreover, when the fuel cell system is mounted on a mobile body, as thedriving state of the associated device, an operation state of a fan foruse in cooling the fuel cell or a motor, or a blower for use in blowingair from an air conditioner of a passenger chamber may be applied.

When such a constitution is employed, for example, the operation soundof the injector is superimposed on the radiant sound from the fan or thelike, whereby the operation sound of the injector can be hidden orobscured by the radiant sound from the fan or the like, and it can beprevented that the operation sound of the injector becomes harsh.

Moreover, when the fuel cell system is mounted on the mobile body, asthe driving state of the associated device, a movement state of themobile body, for example, a movement speed or an accelerated state maybe applied.

In a case where such a constitution is employed, when the movement speedis high, the injector is operated, whereby the operation sound of theinjector can be hidden or obscured by a running sound (e.g., noises oftires on a road or a hissing sound), and it can be prevented that thisoperation sound becomes harsh.

Furthermore, the injector is operated in the accelerated state, that is,an environment during acceleration in which generation of the hissingsound generated in accordance with the movement (the acceleration) ofthe mobile body, a noise during braking or the like is not easilynoticed, whereby it can be prevented that this operation sound becomesharsh. It is to be noted that the accelerated state of the mobile bodyhas correlation with respect to a generated current of the fuel cell, ademanded load (a demanded amount of the power to be generated) from anelectric load (e.g., the motor) connected to the fuel cell or anaccelerator open rate, so that the operation of the injector may becontrolled based on at least one of these factors.

In addition, in the fuel cell system, the control means may control thedrive frequency of the injector based on the frequency of the radiantsound from the associated device.

When such a constitution is employed, for example, the drive frequencyof the injector is matched with the frequency of the radiant sound fromthe associated device, or the frequency of the radiant sound from theassociated device is set to an integral multiple of the drive frequencyof the injector, whereby the operation sound of the injector can behidden or obscured by the radiant sound from the associated device, andit can be prevented that the operation sound of the injector becomesharsh.

Moreover, for example, a phase of the drive frequency of the injector isappropriately displaced from that of the radiant sound from theassociated device, that is, the injector is operated in an environmentin which the generation of the noise is not easily noticed, whereby theoperation sound of the injector is not noticed, and it can be preventedthat the operation sound of the injector becomes harsh.

In the fuel cell system, the control means may change a permissiblerange of a pressure deviation of the injector based on the driving stateof the associated device including the fuel cell system.

To change the permissible range of a pressure deviation, for example, afirst control state in which an opening/closing operation of theinjector is subjected to feedback control based on a deviation between adetected value of a secondary pressure of the injector and a targetcontrol value may be changed to a second control state in whichexecution of the feedback control is prohibited to raise the pressure toa predetermined target pressure at a time when the secondary pressure ofthe injector lowers to a predetermined lower limit pressure.

Moreover, to change the permissible range of a pressure deviation, forexample, a first control state in which when a deviation between adetected value of a secondary pressure of the injector and a targetcontrol value is less than a predetermined value, the deviation isregarded as “0”, whereas when the deviation has the predetermined valueor more, an opening/closing operation of the injector is subjected tofeedback control based on the deviation may be changed to a second statein which the predetermined value is increased as compared with the firstcontrol state.

When the permissible range of a pressure deviation is changed asdescribed above, the number of operation times of the injectordecreases, and as a result, the generation of the harsh operation soundcan be inhibited.

Furthermore, when the fuel cell system is mounted on the mobile body,the control means may change the permissible range of a pressuredeviation of the injector only during an idle operation of the mobilebody.

When such a constitution is employed, it is possible to reduce thenumber of the operation times of the injector during an idle operationhaving high quietness as compared with another operation state.

In a case where the radiant sound generated in accordance with thedriving of the associated device is reduced, the control means mayprohibit the operation of the injector until a secondary pressure of theinjector lowers to a predetermined lower limit pressure.

When such a constitution is employed, the number of the operation timesof the injector in a situation where higher quietness is demanded can bereduced.

Moreover, when the secondary pressure of the injector lowers to thelower limit pressure, the control means may allow the operation of theinjector to raise the secondary pressure to a predetermined pressure.

When such a constitution is employed, a time from a time when thesecondary pressure of the injector raises to the predetermined pressureto a time when the secondary pressure lowers to the lower limit pressurenext can be earned, and eventually, the number of the operation times ofthe injector can be reduced.

The fuel cell system of the present invention is a fuel cell systemmounted on a mobile body, comprising: a fuel cell which receives supplyof a gas to generate a power; an injector which is provided in a gassupply channel of the fuel cell and which adjusts a state of the gas onan upstream side of the gas supply channel to supply the gas to adownstream side; and control means for controlling an operation of theinjector based on a movement state of the mobile body.

Moreover, the injector may include an inner channel which connects anupstream side of the injector to a downstream side thereof, a valve bodywhich is movably arranged in the inner channel and in which an openingarea of the inner channel is varied based on a movement position of thevalve body, and a valve body driving section which drives the valve bodywith an electromagnetic driving force.

A method for operating a fuel cell system according to the presentinvention is a method for operating a fuel cell system including a fuelcell which receives supply of a gas to generate a power and an injectorwhich is provided in a gas supply channel of the fuel cell and whichadjusts a state of the gas on an upstream side of the gas supply channelto supply the gas to a downstream side, the method comprising:controlling an operation of the injector based on a driving state of anassociated device including the fuel cell system.

According to such a constitution, the injector is operated, for example,in a state in which the operation sound of the injector does not easilybecome harsh, whereby it can be prevented that the operation sound ofthe injector becomes harsh.

According to the present invention, there can be provided a highlyresponsive fuel cell system in which a supply pressure of a fuel gas canappropriately be changed based on an operation state of a fuel cell andin which an operator does not easily care about an operation sound of aninjector, and a method for operating the system can also be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a constitution diagram of a fuel cell system according to anembodiment of the present invention;

FIG. 2 is a control block diagram showing a control configuration of acontrol device of a fuel cell system shown in FIG. 1;

FIG. 3 is a sectional view of an injector of the fuel cell system shownin FIG. 1;

FIG. 4 is a time chart showing the control configuration of the controldevice of the fuel cell system shown in FIG. 1;

FIG. 5 is a time chart showing the control configuration of the controldevice of the fuel cell system shown in FIG. 1;

FIG. 6 is a flow chart showing an operation method of the fuel cellsystem shown in FIG. 1;

FIG. 7 is a constitution diagram showing a modification of the fuel cellsystem shown in FIG. 1; and

FIG. 8 is a constitution diagram showing a modification of the fuel cellsystem shown in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

A fuel cell system 1 according to an embodiment of the present inventionwill hereinafter be described with reference to the drawings. In thepresent embodiment, an example in which the present invention is appliedto a car-mounted power generation system of a fuel cell vehicle (amobile body) will be described.

First, a constitution of the fuel cell system 1 according to theembodiment of the present invention will be described with reference toFIG. 1.

As shown in FIG. 1, the fuel cell system 1 according to the presentembodiment includes a fuel cell 10 which receives supply of a reactivegas (an oxidizing gas and a fuel gas) to generate a power, and thesystem also includes an oxidizing gas piping system 2 which supplies airas the oxidizing gas to the fuel cell 10, a hydrogen gas piping system 3which supplies a hydrogen gas as the fuel gas to the fuel cell 10, acontrol device (control means) 4 which integrally controls the wholesystem and the like.

The fuel cell 10 has a stack structure in which a required number ofunitary cells for receiving the supply of the reactive gas to generatethe power are laminated. The power generated by the fuel cell 10 issupplied to a power control unit (PCU) 11. The PCU 11 includes aninverter arranged between the fuel cell 10 and a traction motor 12, aDC-DC converter and the like. Moreover, a current sensor 13 whichdetects a current during the power generation is attached to the fuelcell 10.

The oxidizing gas piping system 2 includes an air supply channel 21which supplies the oxidizing gas (air) humidified by a humidifier 20 tothe fuel cell 10, an air discharge channel 22 which guides, to thehumidifier 20, an oxidizing off gas discharged from the fuel cell 10,and an exhaust channel 23 for guiding the oxidizing off gas from thehumidifier 20. The air supply channel 21 is provided with an aircompressor 24 which takes the oxidizing gas from atmospheric air to feedthe gas under pressure to the humidifier 20.

The hydrogen gas piping system 3 includes a hydrogen tank 30 as a fuelsupply source which stores the hydrogen gas having a high pressure(e.g., 70 MPa), a hydrogen supply channel 31 as a fuel supply channelfor supplying the hydrogen gas of the hydrogen tank 30 to the fuel cell10, and a circulation channel 32 for returning, to the hydrogen supplychannel 31, a hydrogen off gas discharged from the fuel cell 10. Thehydrogen gas piping system 3 is one embodiment of a fuel supply systemof the present invention.

It is to be noted that instead of the hydrogen tank 30, a reformer whichforms a hydrogen-rich reformed gas from a hydrocarbon-based fuel, and ahigh-pressure gas tank which brings the reformed gas formed by thisreformer into a high-pressure state to accumulate the pressure may beemployed as the fuel supply source. Alternatively, a tank having ahydrogen occluded alloy may be employed as the fuel supply source.

The hydrogen supply channel 31 is provided with a shut valve 33 whichshuts or allows the supply of the hydrogen gas from the hydrogen tank30, a regulator 34 which adjusts the pressure of the hydrogen gas, andan injector 35. On an upstream side of the injector 35, a primarypressure sensor 41 and a temperature sensor 42 which detect a pressureand a temperature of the hydrogen gas in the hydrogen supply channel 31,respectively, are provided. Furthermore, on a downstream side of theinjector 35 which is an upstream side of a joining portion of thehydrogen supply channel 31 and the circulation channel 32, there isprovided a secondary pressure sensor 43 which detects a pressure of thehydrogen gas in the hydrogen supply channel 31.

The regulator 34 is a device which adjusts an upstream pressure (aprimary pressure) of the regulator into a beforehand set secondarypressure. In the present embodiment, a mechanical pressure reductionvalve which reduces the primary pressure is employed as the regulator34. As a constitution of the mechanical pressure reduction valve, aknown constitution may be employed which has a housing provided with aback pressure chamber and a pressure adjustment chamber formed via adiaphragm and in which the primary pressure is reduced into apredetermined pressure owing to a back pressure of the back pressurechamber to form a secondary pressure in the pressure adjustment chamber.

In the present embodiment, as shown in FIG. 1, two regulators 34 arearranged on the upstream side of the injector 35, whereby the upstreampressure of the injector 35 can effectively be reduced. Therefore, adegree of freedom in design of a mechanical structure (a valve body, ahousing, a channel, a driving device and the like) of the injector 35can be raised.

Moreover, the upstream pressure of the injector 35 can be reduced, sothat it can be prevented that the valve body of the injector 35 does noteasily move owing to increase of a pressure difference between theupstream pressure and a downstream pressure of the injector 35.Therefore, a variable pressure adjustment range of the downstreampressure of the injector 35 can be broadened, and lowering of a responseproperty of the injector 35 can be inhibited.

The injector 35 is an electromagnetic driving type opening/closing valvein which the valve body is directly driven with an electromagneticdriving force in a predetermined drive cycle and disposed away from avalve seat, whereby a gas state such as a gas flow rate or a gaspressure can be adjusted. The injector 35 includes the valve seat havingan injection hole which injects a gas fuel such as the hydrogen gas, andalso includes a nozzle body which supplies and guides the gas fuel tothe injection hole, and the valve body movably received and held in anaxial direction (a gas flow direction) with respect to this nozzle bodyto open and close the injection hole.

In the present embodiment, the valve body of the injector 35 is drivenby a solenoid which is an electromagnetic driving device, and apulse-like excitation current supplied to this solenoid can be turned onor off to switch an opening area of each injection hole in two stages,multiple stages, a continuous (stepless) manner or a linear manner.

A gas injection time and a gas injection timing of the injector 35 arecontrolled based on a control signal output from the control device 4,whereby a flow rate and a pressure of the hydrogen gas are preciselycontrolled. In the injector 35, the valve (the valve body and the valveseat) is directly driven with the electromagnetic driving force to openor close, and a drive cycle of the valve can be controlled into a highlyresponsive region, so that the injector has a high response property.

In the injector 35, to supply the gas with a demanded flow rate to thedownstream side of the injector, at least one of an opening area (anopen rate) and an opening time of the valve body provided in a gaschannel of the injector 35 is changed, whereby a flow rate (or ahydrogen molecular concentration) of the gas to be supplied to thedownstream side (a fuel cell 10 side) is adjusted.

It is to be noted that the valve body of the injector 35 is opened orclosed to adjust the gas flow rate, and the pressure of the gas to besupplied to the downstream side of the injector 35 is reduced ascompared with the gas pressure on the upstream side of the injector 35,so that the injector 35 can be interpreted as a pressure adjustmentvalve (a pressure reduction valve, a regulator). Moreover, in thepresent embodiment, the injector can be interpreted as a variablepressure adjustment valve capable of changing an adjustment amount (areduction amount) of the upstream gas pressure of the injector 35 sothat the pressure meets a demanded pressure in a predetermined pressurerange based on a gas demand.

It is to be noted that in the present embodiment, as shown in FIG. 1,the injector 35 is arranged on the upstream side of a joining portion A1of the hydrogen supply channel 31 and the circulation channel 32.Moreover, as shown by broken lines in FIG. 1, in a case where aplurality of hydrogen tanks 30 are employed as a fuel supply source, theinjector 35 is arranged on the downstream side of a portion (a hydrogengas joining portion A2) in which the hydrogen gases supplied from thehydrogen tanks 30 are joined.

The circulation channel 32 is connected to a discharge channel 38 via agas-liquid separator 36 and an exhaust discharge valve 37. Thegas-liquid separator 36 collects a water content from the hydrogen offgas. The exhaust discharge valve 37 operates based on a command from thecontrol device 4 to discharge (purge), from the system, the watercontent collected by the gas-liquid separator 36 and the hydrogen offgas including impurities in the circulation channel 32.

Moreover, the circulation channel 32 is provided with a hydrogen pump 39which pressurizes the hydrogen off gas in the circulation channel 32 tofeed the gas toward the hydrogen supply channel 31. It is to be notedthat the gas in the discharge channel 38 is diluted by a diluter 40 tojoin the gas in the exhaust channel 23. It is to be noted that thehydrogen off gas discharged via the exhaust discharge valve 37 and thedischarge channel 38 is diluted by the diluter 40 to join an oxidizingoff gas in the exhaust channel 23.

The control device 4 detects an operation amount of an accelerationoperating device (an accelerator or the like) provided in a vehicle, andreceives control information such as a demanded acceleration value(e.g., a demanded power generation amount from a load device such as thetraction motor 12) to control operations of various units in the system.

It is to be noted that the load device is a generic power consumptiondevice including, in addition to the traction motor 12, an auxiliarydevice (e.g., the compressor 24, the hydrogen pump 39, a motor of acooling pump or the like) required for operating the fuel cell 10, anactuator for use in any type of device (a change gear, a wheel controldevice, a steering device, a suspension device or the like) associatedwith running of the vehicle, an air conditioning device (an airconditioner) of a passenger space, illumination or audio.

Among these devices or attached devices, a device which generates aradiant sound in accordance with driving corresponds to an associateddevice of the present invention, but the device is not limited to anillustrated device.

The control device 4 is constituted of a computer system (not shown).Such a computer system is constituted of a CPU, a ROM, a RAM, a HDD, aninput/output interface, a display and the like, and the CPU reads anytype of control program recorded in the ROM to execute the program,whereby various control operations are realized.

Specifically, as shown in FIG. 2, the control device 4 calculates anamount (hereinafter referred to as the “hydrogen consumption”) of thehydrogen gas consumed by the fuel cell 10 based on an operation state ofthe fuel cell 10 (a current value during power generation of the fuelcell 10 detected by the current sensor 13) (a fuel consumptioncalculating function: B1). In the present embodiment, the hydrogenconsumption is calculated and updated for each calculation cycle of thecontrol device 4 by use of a specific calculation formula indicating arelation between the current value of the fuel cell 10 and the hydrogenconsumption.

Moreover, the control device 4 calculates a target pressure value (atarget gas supply pressure with respect to the fuel cell 10) of thehydrogen gas in a downstream position of the injector 35 based on theoperation state of the fuel cell 10 (the current value of the fuel cell10 during the power generation detected by the current sensor 13) (atarget pressure value calculating function: B2). In the presentembodiment, the target pressure value in a position where the secondarypressure sensor 43 is arranged (a pressure adjustment position as aposition where pressure adjustment is demanded) is calculated andupdated for each calculation cycle of the control device 4 by use of aspecific map indicating a relation between the current value of the fuelcell 10 and the target pressure value.

Furthermore, the control device 4 calculates a feedback correction flowrate based on a deviation between the calculated target pressure valueand a detected pressure value in the downstream position (the pressureadjustment position) of the injector 35 detected by the secondarypressure sensor 43 (a feedback correction flow rate calculatingfunction: B3). The feedback correction flow rate is a hydrogen gas flowrate (a pressure difference reducing correction flow rate) to be addedto the hydrogen consumption in order to reduce the deviation between thetarget pressure value and the detected pressure value. In the presentembodiment, the feedback correction flow rate is calculated and updatedfor each calculation cycle of the control device 4 by use of a targetfollow-up type control of PI control or the like.

In addition, the control device 4 calculates a feed forward correctionflow rate corresponding to a deviation between the previously calculatedtarget pressure value and the presently calculated target pressure value(a feed forward correction flow rate calculating function: B4). The feedforward correction flow rate is a fluctuation (a pressure differencecorresponding correction flow rate) of the hydrogen gas flow rate due toa fluctuation of the target pressure value. In the present embodiment,the feed forward correction flow rate is calculated and updated for eachcalculation cycle of the control device 4 by use of a specificcalculation formula indicating a relation between the deviation of thetarget pressure value and the feed forward correction flow rate.

Moreover, the control device 4 calculates an upstream static flow rateof the injector 35 based on an upstream gas state of the injector 35 (ahydrogen gas pressure detected by the primary pressure sensor 41 and ahydrogen gas temperature detected by the temperature sensor 42) (astatic flow rate calculating function: B5). In the present embodiment, astatic flow rate is calculated and updated for each calculation cycle ofthe control device 4 by use of a specific calculation formula indicatinga relation between the upstream hydrogen gas pressure and temperature ofthe injector 35 and the static flow rate.

Furthermore, the control device 4 calculates an invalid injection timeof the injector 35 based on the upstream gas state (the pressure and thetemperature of the hydrogen gas) of the injector 35 and the appliedvoltage (an invalid injection time calculating function: B6). Here, theinvalid injection time is a time required from a time when the injector35 receives a control signal from the control device 4 to a tome wheninjecting is actually started. In the present embodiment, the invalidinjection time is calculated and updated for each calculation cycle ofthe control device 4 by use of a specific map indicating a relationamong the pressure and temperature of the hydrogen gas on the upstreamside of the injector 35, the applied voltage and the invalid injectiontime.

In addition, the control device 4 adds up the hydrogen consumption, thefeedback correction flow rate and the feed forward correction flow rateto calculate an injection flow rate of the injector 35 (an injectionflow rate calculating function: B7). Subsequently, the control device 4multiplies, by a drive cycle of the injector 35, a value obtained bydividing the injection flow rate of the injector 35 by the static flowrate to calculate a basic injection time of the injector 35, and adds upthis basic injection time and the invalid injection time to calculate atotal injection time of the injector 35 (a total injection timecalculating function: B8). Here, the drive cycle is a stepped (on/off)waveform-like period indicating an opening/closing state of theinjection hole of the injector 35. In the present embodiment, thecontrol device 4 sets the drive cycle to a constant value.

Then, the control device 4 outputs a control signal for realizing thetotal injection time of the injector 35 calculated through theabove-mentioned procedure, whereby the gas injection time and the gasinjection timing of the injector 35 are controlled to adjust the flowrate and the pressure of the hydrogen gas to be supplied to the fuelcell 10.

During a usual operation of the fuel cell system 1, the hydrogen gas issupplied from the hydrogen tank 30 to a fuel electrode of the fuel cell10 via the hydrogen supply channel 31, and the humidified and adjustedair is supplied to an oxidation electrode of the fuel cell 10 via theair supply channel 21, to generate a power. In this case, a power (ademanded power) to be extracted from the fuel cell 10 is calculated bythe control device 4, and the hydrogen gas and air are supplied into thefuel cell 10 as much as amounts corresponding to the amount of thegenerated power. In the present embodiment, a pressure of the hydrogengas to be supplied to the fuel cell 10 during such a usual operation isprecisely controlled.

The above-mentioned injector 35 has a structure shown in FIG. 3, and hasa metal-made cylinder 54 constituting a part of the hydrogen supplychannel (a gas supply channel) 31 and provided with an inner channel 53having one port portion 51 arranged on the side of the hydrogen tank 30of the hydrogen supply channel 31 and the other port portion 52 arrangedon the side of the fuel cell 10 of the hydrogen supply channel 31. Thiscylinder 54 is provided with a first passage portion 56 connected to theport portion 51, a second passage portion 57 connected to a side of thisfirst passage portion 56 opposite to the port portion 51 and having adiameter larger than that of the first passage portion 56, a thirdpassage portion 58 connected to a portion of this second passage portion57 opposite to the first passage portion 56 and having a diameter largerthan that of the second passage portion 57, and a fourth passage portion59 connected to a portion of the third passage portion 58 opposite tothe second passage portion 57 and having a diameter smaller than that ofthe second passage portion 57 and the third passage portion 58, andthese portions constitute the inner channel 53.

Moreover, the injector 35 has a valve seat 61 constituted of a sealablemember provided so as to surround an opening of the fourth passageportion 59 on the side of the third passage portion 58; a metal-madevalve body 65 having a cylindrical portion 62 movably inserted into thesecond passage portion 57 and a bevel portion 63 having a diameterlarger than that of the second passage portion 57 arranged in the thirdpassage portion 58, the bevel portion 63 being provided with an obliquecommunication hole 64; a spring 67 having one end inserted into thecylindrical portion 62 of the valve body 65 and the other end engagedwith a stopper 66 formed in the first passage portion 56 to allow thevalve body 65 to abut on the valve seat 61, thereby blocking the innerchannel 53; and a solenoid (an electromagnetic driving device, a valvebody driving section) 69 which moves the valve body 65 against an urgingforce of the spring 67 until the valve body abuts on a stepped portion68 of the third passage portion 58 on the second passage portion 57side, whereby the valve body 65 is disposed away from the valve seat 61to connect the inner channel 53 in the communication hole 64.

As described above, in the injector 35, during driving for connectingthe inner channel 53, the metal-made valve body 65 moves in themetal-made cylinder 54 to abut on the stepped portion 68 of the cylinder54, so that an operation sound is generated. Such an operation soundbecomes harsh for an operator such as a driver or a passenger as thecase may be. In particular, the injector 35 of the present embodiment isa gas state variable supply device of an electromagnetic driving systemdriven at a high frequency, so that the operation sound of the injectoris a remarkable noise.

To solve the problem, in the present embodiment, while satisfying theabove-mentioned control conditions, the control device 4 drives andcontrols the injector 35 in accordance with a driving state of anassociated device as follows. For example, the control device drives andcontrols the injector 35 in accordance with an operation state of theair compressor (the associated device, a pump) 24 as one of theauxiliary devices. That is, the air compressor 24 generates pulsation ofsuction and discharge to generate the operation sound (a radiant sound)corresponding to the pulsation.

Specifically, in a root type air compressor, a rotary fourth or eighthoperation sound is generated at a frequency of 40 Hz during 1600rotations, at a frequency of 80 Hz during 1200 rotations, and at afrequency of 120 Hz during 1800 rotations. In a scroll type aircompressor, a rotary primary operation sound is generated at a frequencyof 10 Hz during 1600 rotations, at a frequency of 20 Hz during 1200rotations, and at a frequency of 30 Hz during 1800 rotations. In a screwtype air compressor using four-tooth rotor and six-tooth rotor, a rotarysixth operation sound is generated at a frequency of 60 Hz during 1600rotations, at a frequency of 120 Hz during 1200 rotations, and at afrequency of 180 Hz during 1800 rotations. Therefore, the injector 35 isdriven at a frequency of, for example, about 100 Hz or less based onsuch a frequency of the operation sound of the air compressor 24.

In a case where the drive frequency of the injector 35 is controlledbased on the frequency of the operation sound accompanying the pulsationof the air compressor 24 indicating the operation state of the aircompressor 24, for example, the frequency (a noise frequency due to pumppulsation) of the operation sound of the air compressor 24 including aphase is manufactured with the drive frequency of the injector 35.

That is, in a case where the operation sound of the air compressor 24 isgenerated at a frequency shown in FIG. 4( a), as shown in FIG. 4( b), ata peak of the operation sound of the air compressor 24, the injector 35is driven at a timing t1 of rising of the operation sound of the aircompressor 24, and the driving of the injector 35 is stopped at a timingt2 before a noise level of the air compressor 24 lowers.

That is, the drive frequency of the injector 35 is matched with thefrequency of the operation sound of the air compressor 24, whereby thevalve of the injector 35 can be opened while the sound of the aircompressor 24 is emitted. In consequence, the operation sound of theinjector 35 is muffled by the operation sound of the air compressor 24which emits a larger operation sound, and could not be heard by thepassenger. Here, in a case where the injector 35 is driven at a risingtiming of the operation sound of the air compressor 24, the noise of theinjector 35 during the driving when the noise is largest can moreeffectively be muffled.

Moreover, when the drive frequency of the injector 35 is controlledbased on the frequency of the operation sound of the air compressor 24,the frequency of the operation sound of the air compressor 24 is set toan integral multiple of the drive frequency of the injector 35, and thephases are matched.

That is, as shown in FIG. 4( c), control is performed every othergeneration of the operation sound of the air compressor 24 so that atthe peak of the operation sound of the air compressor 24, the injector35 is driven at the rising timing t1 of the operation sound of the aircompressor 24, and the driving of the injector 35 is stopped at alowering timing t3 of the operation sound of the air compressor 24. Atthis time, while the sound of the air compressor 24 is emitted, thevalve of the injector 35 is kept to open, whereby an injection amount isincreased.

In consequence, the injector 35 can be driven so that the frequency ofthe operation sound of the air compressor 24 becomes the integralmultiple (double in FIG. 4( c)) of the drive frequency of the injector35, whereby the operation sound of the injector 35 can be hidden orobscured by the operation sound of the air compressor 24 in the samemanner as described above, and it can be prevented that the operationsound of the injector 35 becomes harsh. In addition, the number of thedriving times of the injector 35 can be reduced, and it can further beprevented that the operation sound of the injector 35 becomes harsh.

Furthermore, in a case where the drive frequency of the injector 35 iscontrolled based on the frequency of the operation sound of the aircompressor 24, for example, the frequency of the operation sound of theair compressor 24 is set to be equal to the drive frequency of theinjector 35, and the phases are appropriately displaced. For example, asshown in FIG. 4( d), for example, the phase of the drive frequency ofthe injector 35 is displaced from that of the operation sound of the aircompressor 24 so that the operation sound is generated between peakgeneration intervals (t4 and t5) of the operation sound of the aircompressor 24.

As described above, the injector 35 is operated so that the operationsound is periodically stably generated together with the operation soundof the air compressor 24. That is, the injector 35 can be operated in anenvironment in which the generation of the noise is not easily noticed,whereby the operation sound of the injector 35 is not cared, and it canbe prevented that the operation sound of the injector 35 becomes harsh.

It is to be noted that the injector 35 may be driven so that theoperation sound is generated between the generation intervals of theoperation sound of the air compressor 24, but the injector may be drivensubstantially in the center of the intervals as long as the operationsound of the air compressor 24 is eliminated.

Moreover, when the operation sound of the air compressor 24 is small,for example, when a vehicle speed is less than a predetermined valueand/or when the generated current of the fuel cell 10 is less than apredetermined value as in an idle operation, a load demand (demandedpower generation) with respect to the fuel cell 10 is small. Even whenthe pressures of the hydrogen gas and air slightly change, the powergeneration stability is not influenced. In consequence, the operation ofthe injector 35 can be prohibited (limited) in such a driven state ofthe air compressor 24.

That is, when the operation sound of the air compressor 24 has apredetermined value or less, the injecting of the injector 35 isprohibited, whereas when the operation sound of the air compressor 24exceeds the predetermined value, the injector is driven as usual,whereby the operation sound of the injector 35 can be muffled by theoperation sound of the air compressor 24. Such a noise countermeasure isespecially effective in a situation in which quietness is relativelyhigh as in the idle operation, as compared with another operation state.

However, the prohibition of the injecting of the injector 35 cannot becontinued to be maintained. Therefore, when the operation sound of theair compressor 24 has the predetermined value or less, the secondarypressure sensor 43 to detect the pressure of the hydrogen gas in thehydrogen supply channel 31 is monitored. In a case where the pressure ofthe hydrogen gas in the hydrogen supply channel 31 detected by thesecondary pressure sensor 43 is a predetermined pressure or less, duringsuch control as to drive the injector 35, the control is loosened sothat a permissible range of a pressure deviation of the hydrogen gas inthe hydrogen supply channel 31 detected by the secondary pressure sensor43 enlarges as much as possible.

As an example in which the control is loosened so as to enlarge thispermissible range of a pressure deviation, first, a first control statein which an opening/closing operation of the injector 35 is subjected tofeedback control based on a pressure deviation between a present value(a detected value) of a secondary pressure detected by the secondarypressure sensor 43 and a target value (a target control value) as inusual control is sometimes changed to a second control state in whichwhen execution of such feedback control is daringly prohibited to raisethe secondary pressure to a predetermined target pressure at a time whenthe secondary pressure of the injector 35 is lowered to a predeterminedlower limit pressure.

Moreover, as a second example, a first control state in which when thepressure deviation between the present value (the detected value) of thedetected secondary pressure of the injector 35 and the target value (thetarget control value) is less than the predetermined value, thedeviation is regarded as “0”, whereas when the deviation has thepredetermined value or more, the opening/closing operation of theinjector 35 is subjected to the feedback control is sometimes changed toa second state in which the predetermined value is increased as comparedwith the first control state, in other words, a dead zone in which thepressure deviation is forcibly regarded as “0” is broadened.

Furthermore, as a third example, a first control state in which anopening/closing operation of the injector 35 is controlled so that adrive cycle (a basic period) of the injector 35 is constant is sometimeschanged to a second control state in which an injection amount of theinjector 35 per drive cycle is forcibly increased (or an injection timeis lengthened) as compared with this first control state.

Then, as a fourth example, a first control state in which theopening/closing operation of the injector 35 is controlled so that aninjection amount or an injection time of the injector 35 per one drivecycle (a basic period) becomes constant is sometimes changed to a secondcontrol state in which the one drive cycle (the basic period) isforcibly lengthened as compared with the first control state.

Next, for example, the first example will specifically be described.During normal control shown in FIG. 5( a), the injector 35 is driven(injected) between time t11 and t12 based on the pressure deviationbetween the present value and the target value. With this driving, thepressure of the hydrogen gas in the hydrogen supply channel 31 rises asshown in the drawing. On the other hand, in the first example shown inFIG. 5( b), the injector 35 is not driven as a result of the feedbackcontrol based on the above-mentioned pressure deviation, till time t13when the pressure of the hydrogen gas in the hydrogen supply channel 31lowers to a predetermined lower limit value P_(L). However, the hydrogengas pressure lowers to the lower limit value P_(L), the injector 35 isdriven between the time t13 and t14.

Then, when the pressure of the hydrogen gas in the hydrogen supplychannel 31 during this driving (t13 and t14) is raised as much aspossible (raised to, for example, a predetermined upper limit value (apredetermined target pressure) P_(H)), a time t15 can be earned untilthe pressure next lowers to the predetermined lower limit value P_(L) torestart driving the injector 35. Therefore, the number of emissions ofthe operation sound of the injector 35 can be reduced, and it can beprevented that the operation sound becomes harsh.

Even in this case, when the operation sound of the air compressor 24exceeds the predetermined value, the injector 35 is driven as usual,whereby the operation sound of the injector 35 can be muffled by theoperation sound of the air compressor 24.

As described above, when the operation sound of the air compressor 24 issmall, that is, as shown in FIG. 6, when the operation sound of the aircompressor 24 is smaller than a predetermined lower limit value (stepS1), control is loosened so as to enlarge the permissible range of apressure deviation as much as possible (step S2). In a case where thenumber of the driving times of the injector 35 is reduced, when anaccelerator open rate per unit time is increased in excess of apredetermined upper limit value (step S3: YES), the permissible range ofa pressure deviation is set to a usual setting (step S4), and theinjecting of the injector 35 may be performed as usual.

That is, the control of the step S2 in which the permissible range of apressure deviation is set to be large based on the accelerator open ratemay be released. In this case, drop of the gas pressure during vehicleacceleration can be prevented, and an acceleration response property anda product property can be improved. Needless to say, even in a casewhere the driving of the injector 35 is prohibited at a time when theoperation sound of the air compressor 24 is small, the prohibition canbe released based on the accelerator open rate.

It is to be noted that during the usual control, as described above, thefeedback control is performed based on the pressure deviation obtainedby “the present value minus the target value” of the detected secondarypressure of the injector 35, and the value is brought close to thetarget value as much as possible while changing the target controlvalue. However, as described above, when the operation sound of the aircompressor 24 is small, the load demand (the power generation demand) ofthe fuel cell 10 is small. It is sometimes assumed that even when thepressures of the hydrogen gas and the air slightly change, the powergeneration stability is not influenced. To solve the problem, in such acase, the control state may be shifted from a usual control time as thefirst control state to the second control state in which a pressurecontrol range is broadened as compared with the usual control time.

For example, in a case where an absolute value of the pressure deviationis a predetermined value or less while a target pressure adjustmentwidth is maximized, the dead zone in which the pressure deviation isregarded as “0” is enlarged, and the pressure control range is broadenedas compared with the usual control, whereby an effect similar to theabove effect can be obtained. This example corresponds to the secondexample in which the control is loosened so as to enlarge thepermissible range of a pressure deviation.

Furthermore, a magnitude of the operation sound of the air compressor 24substantially has a proportionality relation with respect to the vehiclespeed, so that the vehicle speed may be applied instead of the operationsound of the air compressor 24, and the operation of the injector 35 canbe controlled based on this vehicle speed. That is, when the vehiclespeed is low, the operation sound of the air compressor 24 is small, anda running sound is small. Therefore, in a case where the vehicle speedhas a predetermined value or less, the injecting of the injector 35 isprohibited, or the control is loosened so as to enlarge the permissiblerange of a pressure deviation as much as possible, thereby reducing thenumber of the injecting times of the injector 35.

On the other hand, when the vehicle speed increase, the magnitude of theoperation sound of the air compressor 24 enlarges, and a running soundsuch as a noise of a tire on a road or a hissing sound enlarges.Therefore, even in a case where the vehicle speed exceeds thepredetermined value and the injector 35 is driven as usual, theoperation sound of the injector 35 can be muffled by the operation soundor the running sound of the air compressor 24. Therefore, it can beprevented that this operation sound becomes harsh.

The vehicle speed substantially has a proportionality relation withrespect to the number of the injecting times of the injector 35 and thenumber of the rotations of the air compressor 24, so that there is amerit that cooperative control is easily performed. It is to be notedthat it is determined, depending on the vehicle, whether the runningsound or the operation sound of the air compressor 24 is large, so thatit can be selected whether the operation sound of the injector 35 ismuffled mainly by the running sound or the operation sound of the aircompressor 24, depending on the vehicle.

Moreover, examples of the vehicle auxiliary device which can generatesuch a comparatively large operation sound as to muffle the drivingsound of the injector 35 include the air compressor 24, additionally ablower which blows air from an air conditioner (an air conditioningdevice) in a vehicle chamber, or a radiator fan which cools coolingwater for the fuel cell 10 outside the vehicle chamber. Therefore, theoperation of the injector 35 may be controlled in the same manner asdescribed above based on operation states of these devices instead ofthe air compressor 24, that is, an operation sound (a blowing sound) ofthe blower of the air conditioner or an operation sound of the radiatorfan. However, the operation sound of the air compressor 24 is usuallylargest, so that the injector may be controlled in accordance with anoperating situation of the air compressor 24.

Furthermore, the magnitude of the operation sound of the air compressor24 substantially has a proportionality relation with respect to thegenerated current of the fuel cell 10, and also substantially has aproportionality relation with respect to the demanded load of the motor,that is, the accelerator open rate (an accelerated/decelerated state),so that the accelerator open rate is applied instead of the operationsound of the air compressor 24, and the operation of the injector 35 maybe controlled based on this accelerator open rate.

That is, when the accelerator open rate is small, the operation sound ofthe air compressor 24 is small, so that in a case where the acceleratoropen rate has a predetermined value or less, the injecting of theinjector 35 is prohibited, or the control is loosened so as to enlargethe permissible range of a pressure deviation as much as possible,thereby reducing the number of the injecting times of the injector 35.

On the other hand, when the accelerator open rate increases, themagnitude of the operation sound of the air compressor 24 enlarges.Therefore, even in a case where the injector 35 is driven as usual at atime when the accelerator open rate exceeds the predetermined value, theoperation sound of the injector 35 can be muffled by the operation soundof the air compressor 24.

Therefore, it can be prevented that this operation sound becomes harsh.The accelerator open rate substantially has a proportionality relationwith respect to the number of the injecting times of the injector 35 andthe number of the rotations of the air compressor 24, so that there is amerit that the cooperative control is easily performed.

It is to be noted that in a hybrid system provided with two powersources including the fuel cell 10 and a battery, the generated currentof the fuel cell 10 sometimes does not have any proportional relationwith respect to the demanded load of the motor, that is, the acceleratoropen rate. However, even in this case, when the accelerator open rate islarge, that is, the injector 35 is operated in an environment duringacceleration where the generation of the noise is not easily cared,whereby it can be prevented that this operation sound becomes harsh.

It is to be noted that the above-mentioned control is performed aftercompletion of warm-up of the fuel cell 10 (after releasing of outputlimitation). This is because before the warm-up, any power generationrobust property with respect to the pressure is not seen in the fuelcell 10, and it is difficult to apply the control.

In the fuel cell system 1 described above according to the presentembodiment, the operation state (the injection time) of the injector 35can be set based on the operation state (the current value during thepower generation) of the fuel cell 10. Therefore, the supply pressure ofthe hydrogen gas can appropriately be changed based on the operationstate of the fuel cell 10, and a response property can be improved.Moreover, the injector 35 is employed as a flow rate adjustment valve ofthe hydrogen gas and a variable pressure adjustment valve, so thatprecise pressure adjustment (adjustment of the supply pressure of thehydrogen gas to the fuel cell 10) can be performed.

That is, the injector 35 can receive the control signal from the controldevice 4 based on the operation state of the fuel cell 10 to adjust theinjection time and the injection timing of the hydrogen gas, so that thepressure adjustment can more quickly and exactly be performed ascompared with a conventional mechanical variable pressure adjustmentvalve. Moreover, the injector 35 is small-sized, light-weighted andinexpensive as compared with the conventional mechanical variablepressure adjustment valve, so that the whole system that is miniaturizedand inexpensive can be realized.

Moreover, in the fuel cell system 1 according to the above-mentionedembodiment, the control device 4 controls the operation of the injector35 based on the driving state of the associated device, so that theinjector 35 can be operated in a state in which, for example, theoperation sound of the injector 35 does not easily become harsh, and itcan be prevented that the operation sound of the injector 35 becomesharsh.

That is, the control device 4 controls the operation of the injector 35based on the operation state of the air compressor 24, whereby, forexample, the operation sound of the injector 35 is superimposed on theoperation sound of the air compressor 24. In consequence, the operationsound of the injector 35 can be hidden or obscured by the operationsound of the air compressor 24, and it can be prevented that theoperation sound of the injector 24 becomes harsh.

The control device 4 may control the operation of the injector 35 basedon the operation state of the air conditioner. In this case, forexample, when the operation sound of the injector 35 is superimposed onthe operation sound of the air conditioner, the operation sound of theinjector 35 can be hidden or obscured by the operation sound of the airconditioner, so that it can be prevented that the operation sound of theinjector 35 becomes harsh.

Moreover, the control device 4 may control the operation of the injector35 based on the operation state of the radiator fan. In this case, forexample, when the operation sound of the injector 35 is superimposed onthe operation sound of the radiator fan, the operation sound of theinjector 35 can be hidden or obscured by the operation sound of theradiator fan, so that it can be prevented that the operation sound ofthe injector 35 becomes harsh.

Furthermore, in the fuel cell system 1 according to the above-mentionedembodiment, in a case where the system is mounted on a mobile body, thecontrol device 4 can control the operation of the injector 35 based onthe vehicle speed. Therefore, for example, when the vehicle speed ishigh, the injector 35 is operated, whereby the operation sound of theinjector 35 can be hidden or obscured by the running sound of the mobilebody, and it can be prevented that this operation sound becomes harsh.

In addition, in the fuel cell system 1 according to the above-mentionedembodiment, in a case where the system is mounted on the mobile body,the control device 4 can control the operation of the injector 35 basedon the accelerator open rate (the accelerated/decelerated state), sothat the injector 35 is operated, for example, at a time when theaccelerator open rate is large, that is, in an environment during theacceleration where the generation of the noise is not easily cared. Inconsequence, it can be prevented that this operation sound becomesharsh.

Moreover, in the fuel cell system 1 according to the above-mentionedembodiment, the control device 4 can control the drive frequency of theinjector 24 based on the frequency of the operation sound of the aircompressor 24 as the auxiliary device, so that, for example, the drivefrequency of the injector 35 is matched with the frequency of theoperation sound of the air compressor 24, or the frequency of theoperation sound of the air compressor 24 is set to the integral multipleof the drive frequency of the injector 35. In consequence, the operationsound of the injector 35 can be hidden or obscured by the operationsound of the air compressor 24, whereby it can be prevented that theoperation sound of the injector 35 becomes harsh.

Furthermore, the injector 35 is operated, for example, in a case wherethe phase of the drive frequency of the injector 35 is appropriatelydisplaced from the phase of the operation sound of the air compressor24, that is, in the environment where the generation of the noise is noteasily cared. In consequence, the operation sound of the injector 35 isnot noticed, and it can be prevented that the operation sound of theinjector 35 becomes harsh.

It is to be noted that in the above embodiment, the injector has beendescribed in accordance with an example of the injector provided in thehydrogen supply channel 31 of the fuel cell system. However, the presentinvention is applicable to any other injector as long as the injector isprovided in the gas supply channel of the fuel cell system.

As shown in, for example, FIG. 7, in a case where an air supply channel21 for supplying an oxidizing gas (air) to a fuel cell 10 is providedwith a humidifying water supply injector 71 instead of the humidifier20, the present invention is applicable to this injector. Alternatively,as shown in FIG. 8, in a case where a hydrogen supply channel 31 forsupplying a hydrogen gas to a fuel cell 10 is provided with a pneumaticregulator 72 instead of the injector, the present invention isapplicable to a cathode air supply injector 73 for controlling ahydrogen pressure of this pneumatic regulator 72 with an air pressure orthe like.

Moreover, in the above embodiment, an example in which the fuel cellsystem according to the present invention is mounted on the fuel cellvehicle has been described, but the fuel cell system according to thepresent invention may be mounted on any type of mobile body (a robot, aship, an airplane or the like) other than the fuel cell vehicle. Thefuel cell system according to the present invention may be applied to astationary power generation system for use as a power generationequipment for construction (housing, building or the like).

INDUSTRIAL APPLICABILITY

The present invention is broadly applicable to a fuel cell system (or amethod for operating the system), which is highly responsive and capableof appropriately changing a supply pressure of a fuel gas based on anoperation state of a fuel cell, and in which an operator does not easilycare about an operation sound of an injector.

1-19. (canceled)
 20. A fuel cell system comprising: a fuel cell whichreceives supply of a gas to generate a power; an injector which isprovided in a gas supply channel of the fuel cell and which adjusts astate of the gas on an upstream side of the gas supply channel to supplythe gas to a downstream side; and a control device for driving andcontrolling the injector, wherein the control device allows or prohibitsan operation of the injector, or changes a drive cycle so as to hide orobscure an operation sound of the injector from an operator by a radiantsound of an auxiliary device required for operating the fuel cell or adevice attached to the auxiliary device which generates the radiantsound in accordance with driving of the device.
 21. The fuel cell systemaccording to claim 20, wherein the auxiliary device is a pump whichsupplies a fluid to the fuel cell.
 22. The fuel cell system according toclaim 21, wherein the pump is an air compressor which feeds an oxidizinggas under pressure to the fuel cell.
 23. A fuel cell system which ismounted on a mobile body, comprising: a fuel cell which receives supplyof a gas to generate a power; an injector which is provided in a gassupply channel of the fuel cell and which adjusts a state of the gas onan upstream side of the gas supply channel to supply the gas to adownstream side; and a control device for driving and controlling theinjector, wherein the control device allows or prohibits an operation ofthe injector, or changes a drive cycle so as to hide or obscure anoperation sound of the injector from an operator based on an operationsound of an air conditioner in a passenger chamber of the mobile body ora blowing sound.
 24. A fuel cell system which is mounted on a mobilebody, comprising: a fuel cell which receives supply of a gas to generatea power; an injector which is provided in a gas supply channel of thefuel cell and which adjusts a state of the gas on an upstream side ofthe gas supply channel to supply the gas to a downstream side; and acontrol device for driving and controlling the injector, wherein thecontrol device allows or prohibits an operation of the injector, orchanges a drive cycle so as to hide or obscure an operation sound of theinjector from an operator based on an operation sound or a blowing soundof a fan for use in cooling the fuel cell or a motor or a blower for usein blowing air from an air conditioner in a passenger chamber.
 25. Afuel cell system which is mounted on a mobile body, comprising: a fuelcell which receives supply of a gas to generate a power; an injectorwhich is provided in a gas supply channel of the fuel cell and whichadjusts a state of the gas on an upstream side of the gas supply channelto supply the gas to a downstream side; and a control device for drivingand controlling the injector, wherein the control device allows orprohibits an operation of the injector, or changes a drive cycle basedon a movement speed or an accelerated state of the mobile body so as tohide or obscure an operation sound of the injector from an operator. 26.The fuel cell system according to claim 20, wherein the control devicecontrols a drive frequency of the injector based on a frequency of theradiant sound from an auxiliary device required for operating the fuelcell or a device attached to the auxiliary device which generates theradiant sound in accordance with driving of the device.
 27. A fuel cellsystem comprising: a fuel cell which receives supply of a gas togenerate a power; an injector which is provided in a gas supply channelof the fuel cell and which adjusts a state of the gas on an upstreamside of the gas supply channel to supply the gas to a downstream side;and a control device for driving and controlling the injector, whereinthe control device changes a permissible range of a pressure deviationof the injector based on a radiant sound from a device which generatesthe radiant sound, and the permissible range of a pressure deviation ischanged by changing a first control state in which an opening/closingoperation of the injector is subjected to feedback control based on adeviation between a detected value of a secondary pressure of theinjector and a target control value to a second control state in whichexecution of the feedback control is prohibited to raise the pressure toa predetermined target pressure at a time when the secondary pressure ofthe injector lowers to a predetermined lower limit pressure.
 28. A fuelcell system comprising: a fuel cell which receives supply of a gas togenerate a power; an injector which is provided in a gas supply channelof the fuel cell and which adjusts a state of the gas on an upstreamside of the gas supply channel to supply the gas to a downstream side;and a control device for driving and controlling the injector, whereinthe control device changes a permissible range of a pressure deviationof the injector based on a radiant sound from a device which generatesthe radiant sound, and the permissible range of a pressure deviation ischanged by changing a first control state in which when a deviationbetween a detected value of a secondary pressure of the injector and atarget control value is less than a predetermined value, the deviationis regarded as “0”, whereas when the deviation has the predeterminedvalue or more, an opening/closing operation of the injector is subjectedto feedback control based on the deviation to a second state in whichthe predetermined value is increased as compared with the first controlstate.
 29. The fuel cell system according to claim 27, which is mountedon a mobile body, wherein the control device changes the permissiblerange of a pressure deviation of the injector only during an idleoperation of the mobile body.
 30. The fuel cell system according toclaim 28, which is mounted on a mobile body, wherein the control devicechanges the permissible range of a pressure deviation of the injectoronly during an idle operation of the mobile body.
 31. The fuel cellsystem according to claim 20, wherein in a case where the radiant soundfrom the device which generates the radiant sound is hidden or obscuredfrom the operator, the control device prohibits the operation of theinjector until a secondary pressure of the injector lowers to apredetermined lower limit pressure.
 32. The fuel cell system accordingto claim 31, wherein when the secondary pressure of the injector lowersto the lower limit pressure, the control device allows the operation ofthe injector to raise the secondary pressure to a predeterminedpressure.
 33. A fuel cell system which is mounted on a mobile body,comprising: a fuel cell which receives supply of a gas to generate apower; an injector which is provided in a gas supply channel of the fuelcell and which adjusts a state of the gas on an upstream side of the gassupply channel to supply the gas to a downstream side; and a controldevice for allowing or prohibiting an operation of the injector orchanging a drive cycle based on a movement state of the mobile body soas to hide or obscure an operation sound of the injector from anoperator.
 34. The fuel cell system according to claim 20, wherein theinjector includes an inner channel which connects an upstream side ofthe injector to a downstream side thereof, a valve body which is movablyarranged in the inner channel and in which an opening area of the innerchannel is varied based on a movement position of the valve body, and avalve body driving section which drives the valve body with anelectromagnetic driving force.
 35. The fuel cell system according toclaim 33, wherein the injector includes an inner channel which connectsan upstream side of the injector to a downstream side thereof, a valvebody which is movably arranged in the inner channel and in which anopening area of the inner channel is varied based on a movement positionof the valve body, and a valve body driving section which drives thevalve body with an electromagnetic driving force.